U.S. patent number 7,768,250 [Application Number 12/197,580] was granted by the patent office on 2010-08-03 for magnetic indexer for high accuracy hole drilling.
This patent grant is currently assigned to The Boeing Company. Invention is credited to Gregory L. Clark, Gary E. Georgeson, Joseph L. Hafenrichter, Raymond D. Rempt.
United States Patent |
7,768,250 |
Georgeson , et al. |
August 3, 2010 |
Magnetic indexer for high accuracy hole drilling
Abstract
A method for locating a device, which produces a field, with a
probe assembly affected by the field. The method may involve:
placing a device on a first side of a work piece; producing a field
with the device through the work piece; using a robot to hold and
to place a probe assembly adjacent a second side of the work piece;
providing information from the probe assembly to the robot that is
used by the robot to move the probe assembly to substantially
determine a position of the device; determining a location of a
center field axis of the field with the probe assembly; and
providing a physical confirmation of the center field axis to a
user.
Inventors: |
Georgeson; Gary E. (Federal
Way, WA), Hafenrichter; Joseph L. (Redmond, WA), Rempt;
Raymond D. (Woodinville, WA), Clark; Gregory L.
(Issaquah, WA) |
Assignee: |
The Boeing Company (Chicago,
IL)
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Family
ID: |
29400076 |
Appl.
No.: |
12/197,580 |
Filed: |
August 25, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080315869 A1 |
Dec 25, 2008 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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10143242 |
May 9, 2002 |
7498796 |
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Current U.S.
Class: |
324/67;
324/260 |
Current CPC
Class: |
G01D
5/145 (20130101); B23B 51/02 (20130101); B23B
49/00 (20130101); G01V 15/00 (20130101); B23B
2260/128 (20130101); B23B 2270/48 (20130101); B23B
2260/118 (20130101); B23B 2260/0485 (20130101); B23B
2260/10 (20130101); B23B 2270/38 (20130101); B23B
2215/04 (20130101) |
Current International
Class: |
G01R
33/02 (20060101); G01B 7/00 (20060101) |
Field of
Search: |
;324/67,260 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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508347 |
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Sep 1930 |
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DE |
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1013351 |
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Dec 1965 |
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GB |
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2363462 |
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Dec 2001 |
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GB |
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Other References
Honeywell Sensor Products, Three-Axis Magnetic Sensor Hybrid, 4
pages, Oct. 1997. cited by other .
http://homerepair.about.com/od/interiorhomerepair/a/buy-stud-finder.htm,
at least one day prior to Mar. 26, 2008, printed Dec. 7, 2009, 2
Pages. cited by other .
http://home.howstuffworks.com/question271.htm, at least one day
prior to Mar. 26, 2008, printed Dec. 7, 2009, 4 Pages. cited by
other.
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Primary Examiner: Aurora; Reena
Attorney, Agent or Firm: Harness, Dickey & Pierce,
P.L.C.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. patent application Ser.
No. 10/143,242 filed on May 9, 2002. The disclosure of the above
application is incorporated herein by reference.
Claims
What is claimed is:
1. A method for locating a device and a probe assembly relative to
a work piece, where the device and the probe assembly are
positioned on different sides of the work piece, and the probe
assembly is affected by a magnetic field generated by the device,
the method comprising: mounting said probe assembly on a platform
that is moveable relative to a mounting structure, with the
mounting structure being fixable to the work piece; providing said
mounting structure with a manually engageable first axis adjustment
control for enabling a user to move said platform along a first
axis, and a manually engageable second axis adjustment for enabling
the user to move said platform along a second axis perpendicular to
said first axis; placing said device on a first side of the work
piece; producing a field with said device through said work piece;
placing said platform with said probe assembly mounted on said
platform adjacent a second side of said work piece; using
information from said probe assembly to enable the user to adjust
said first and second axis adjustment controls to move the probe
assembly along said first and second axes to substantially
determine a position of the device; determining a location of a
center field axis of said magnetic field with said probe assembly;
and confirming said center field axis to a user.
2. The method of claim 1, wherein: placing a device comprises
placing a magnet against said first side of said work piece.
3. The method of claim 1, wherein mounting said probe assembly on a
platform further comprises: providing at least three probes spaced
apart defining a center probe axis; and fixing said probes in said
movable platform so that said center probe axis is movable.
4. The system of claim 3, wherein said probes and said platform are
moveable relative to a mounting structure fixable to the work
piece; wherein said mounting structure includes a first axis
adjustment and a second axis adjustment; wherein said first axis
adjustment and said second axis adjustment are operable to move
said platform relative to said mounting structure while said
mounting structure remains substantially fixed.
5. The method of claim 3, wherein determining a location of said
center field axis comprises: moving said movable platform relative
to a point on said second side of said surface; using said probes
to sense the magnetic field as said probes are moved over said
surface; and providing a processor to determine the affect on said
probes, said processor determining when said center probe axis is
collinear with the center field axis.
6. The method of claim 3, wherein providing a physical confirmation
of said center field axis comprises providing a visual indication
that said center probe axis, on said second side of said work
piece, is substantially collinear with said center field axis on
said first side of said work piece.
7. The method of claim 1, wherein determining a location of a
center field axis comprises: moving said probe assembly relative to
a point on said second side of said work piece; affecting the probe
assembly with the field as the probe is moved over said work piece;
and providing a processor to determine the affect on said probe
assembly, wherein said processor determines the center field
axis.
8. The method of claim 1, wherein providing a physical confirmation
of said center field axis comprises providing a visual indication
that said center probe axis on said second side of said work piece
is substantially collinear with said center field axis on said
first side of said work piece.
9. A method for locating a device relative to a work piece, where
the device produces a field, with a probe assembly affected by the
field, the method comprising: placing a magnet against a first side
of a work piece; producing a magnetic field with said device
through said work piece; supporting the probe assembly on a
moveable platform positioned adjacent a second side of said work
piece: providing the probe assembly with at least three probes
spaced apart to define a center probe axis; providing a manually
engageable first axis control for enabling a user to manually,
controllably move the moveable platform along a first axis, and a
manually engageable second axis control for enabling the user to
controllably move the moveable platform along a second axis
non-parallel to the first axis. to thus control positioning of the
probe assembly along two non-parallel axes: determining a location
of a center field axis of said field of said magnet with said probe
assembly; and providing a physical confirmation to said user when
said center field axis generated by said magnet is substantially
co-linear with a center field axis of said probe assembly on said
second side of said work piece.
10. The method of claim 9, wherein determining a location of a
center field axis of said magnet comprises: moving said probe
assembly relative to a point on said second side of said work
piece; affecting the probe assembly with the field as the probe is
moved over said work piece; and providing a processor to determine
the affect on said probe assembly, wherein said processor
determines the center field axis.
11. The method of claim 10, wherein said three probes are
equidistantly spaced from one another with said center field axis
of said probe being at an axial center of said three probes.
12. The method of claim 10, wherein providing a confirmation
comprises emitting a light signal.
13. The method of claim 10, wherein determining said location of a
center field axis of said field with said probe assembly comprises
determining when said affect on each of said probes is
substantially equivalent, and then concluding that said center
field axis of said magnet is aligned co-linearly with said center
probe axis of said probe assembly.
14. The method of claim 10, further comprising aligning the probe
assembly in two axes relative to a mounting structure affixed to
the work piece.
15. The method of claim 10, further comprising performing a
machining operation on said work piece.
16. The method of claim 9, further comprising: removably securing
said probe assembly to said mounting platform; providing said
mounting platform with a hole at the center field axis of the probe
assembly; removing the probe assembly from the mounting platform
after it is determined that the center field axis of the probe
assembly is aligned with the center field axis generated by the
magnet; and extending a drill bit through the hole in the mounting
platform and using the drill bit to drill a hole in the work
piece.
17. A method for locating a device relative to a work piece, where
the device produces a field, with a probe assembly affected by the
field, the probe assembly having a center field axis, the method
comprising: placing a magnet against a first side of a work piece;
producing a magnetic field with said device through said work
piece; removably supporting the probe assembly on a moveable
platform positioned adjacent a second side of said work piece, the
movable platform having a hole aligned with the center field axis
of the probe assembly; providing the probe assembly with at least
three probes spaced apart to define a center probe axis; providing
a manually engageable positioning control that enables a user to
manually, controllably move the moveable platform along at least
one axis to thus control positioning of the probe assembly relative
to the work piece; determining a location of a center field axis of
said field of said magnet with said probe assembly; providing a
physical confirmation to said user when said center field axis
generated by said magnet is substantially co-linear with a center
field axis of said probe assembly on said second side of said work
piece; and removing the probe assembly from the moveable platform
to expose the hole to enable a machining operation to be carried
out on the work piece.
18. The method of claim 17, wherein enabling a machining operation
to be carried out on the workpiece comprises extending a drill bit
through the hole and drilling a hole in the work piece.
19. The method of claim 17, wherein providing a manually engageable
positioning control comprises providing a manually engageable first
axis control for enabling the user to move the moveable platform
along a first axis, and providing a manually engageable second axis
control for enabling the user to move the moveable platform along a
second axis perpendicular to the first axis.
Description
TECHNICAL FIELD
The present disclosure relates to a system to precisely form holes,
and more particularly to a system to locate a device and indicate a
location to form a hole.
BACKGROUND
It is often desirable to locate, with a high degree of accuracy and
specificity, locations in a blind area of a working surface. In
particular, if it is desired to affix together two portions of a
structure, where only an outside surface is visible to a work
person, it is often difficult, if not impossible, to precisely and
reproducibly place a fastener between the two portions. This is
particularly relevant in regards to aircraft where the skin of the
aircraft is placed over an internal frame structure and must be
affixed thereto. Once the skin is in place, it is often very
difficult to properly locate a fastener that must first go through
the skin to be affixed to the internal structure of the aircraft.
This situation arises in other construction and manufacturing
instances as well.
One solution has been the attempt to back drill from inside the
structure. That is, to have a work person physically place
themselves inside the structure and then cut through the
sub-structure through the skin. This, however, often creates
impreciseness in the hole creation. For example, the full sized
hole which is formed normal to the skin of the air craft, which is
following the back drilled pilot hole, may be angular. That is
because the hole formed from the inside of the skin can not be
easily formed exactly normal to the skin of the aircraft. In
particular the internal structures of the part may not be normal to
the skin while the hole on through the outside of the skin must be
normal to the skin. Furthermore, it is very hard on the work person
who must crawl into the usually small areas to produce the
holes.
Backmarkers are widely used in the aircraft industry to transfer
holes from the understructure to the outside surface. Backmarkers
consist of a long split piece of thin metal with a pin on one side
and a hole on the other that are in alignment. The pin side is
slipped under the skin to line up with a pilot hole, in the
understructure, and a pilot hole is drilled into the outer skin.
This method does not work on wide parts and thick parts. Deflection
of the split plates and the difficulty of installing the device on
thick parts limits the use to thin sheet metal areas near the edge
of the skin.
Another method is to use a probe or locating device to determine a
precise position on the skin. In particular, the device is first
programmed with locations in three dimensional space. Therefore,
when a surface is placed within reach of the probe, the probe can
determine the location of a point which the probe touches. This,
however, requires an extensive pre-programming and precise
placement of the surface which is to be probed. Using such special
orientation probes increases time and manufacturing costs for many
applications. Also, probing the understructure before drilling has
several shortcomings. When a skin is placed over a built up
structure, the weight of the skin causes the structure and tooling
to deform. It is possible that probed holes will move between
measurements and drilling. Also, temperature changes between
probing and drilling can cause the holes to not align due to growth
or shrinkage to the part and differences in growth between the
upper and lower surfaces. Fastener induced growth and coldworking
of holes in aircraft structure can also shift positions of the
holes between probing and drilling.
In aircraft construction, it is often critical to produce a hole,
for fastening a portion of the airframe to another portion, within
hundredths of an inch. One specific method of construction for
internal airframe structure involves the use of sine wave
topography on the internal structures or beams of the aircraft. To
ensure a sufficiently strong connection, which will withstand the
extreme stresses that an aircraft will encounter, the fastener must
be placed at a peak of the sine wave. Therefore, placement of a
fastener must be extremely precise to ensure that a peak is hit,
rather than a valley or a portion adjacent to the peak. It is also
desirable to precisely locate edges of hidden structure pieces. In
this and many other applications, the precise locating of the
fastener becomes critically important.
SUMMARY
The present disclosure is directed to a magnetic indexer which
locates a device that is producing a magnetic field in a blind or
inaccessible position. A magnet is initially placed on one side of
the work surface such that a magnetic field produced by the magnet
extends through the work surface such that the axis of the magnetic
field is substantially perpendicular to the work surface. The
device, comprising a plurality of probes which are affected by
magnetic fields, is positioned over the opposite side of the work
surface. The probes are then moved over the work surface to
determine the location of the magnet. Once the position of the
magnetic field axis is determined, the work surface is either
marked or worked on through the platform on which the probes are
positioned. In particular, a hole may be reproducibly placed
directly over the magnet even when the underside of the work piece
is not visible. Additionally, with the present disclosure, a work
tool may be very accurately positioned on the work surface without
seeing the underside of the work surface.
A first embodiment of the present disclosure includes a system for
determining a location of a device that produces a field having
varying strengths depending upon a lateral distance from the
device. The system comprises a probe adapted to be affected by the
varying strength of the field produced by the device and which
assists in locating the device. As the probe is moved a processor
determines the field strength affecting the probe. A confirmation
system provides a physical confirmation that the processor has
determined the location of the device with the probe.
A second embodiment of the present disclosure includes a system to
determine a location of a device through a surface. The system
comprises a device, which produces a magnetic field, positioned on
a first side of the surface. A probe is positioned on a second side
of the surface affected by the field. A processor determines the
affect produced in the probe by the field. The processor is adapted
to determine the position of the device based upon the affect of
the field on the probe.
The present disclosure also provides a new method to precisely
locate a position. The method involves locating a device, which
produces a field, with a probe affected by the field. The device is
placed on a first side of a surface. A field is then produced with
the device through the surface. A probe is used on a second side of
the surface to determine a center axis of the field and to provide
a physical confirmation of the center axis of the field. Once the
location of the center axis of the field is determined then work
may be performed at a precise and predetermined location.
Further areas of applicability of the present disclosure will
become apparent from the detailed description provided hereinafter.
It should be understood that the detailed description and specific
examples, while indicating one embodiment of the disclosure, are
intended for purposes of illustration only and are not intended to
limit the scope of the present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
The present disclosure will become more fully understood from the
detailed description and the accompanying drawings, wherein:
FIG. 1 is a perspective view of a preferred embodiment of the
digital magnetizer according to the present disclosure;
FIG. 2 is a side elevational view of the magnetic indexer according
to the present disclosure;
FIG. 3 is a perspective view of the magnetic indexer in use;
FIG. 4 is a perspective view of the platform of the magnetic
indexer after it has been positioned;
FIG. 5 is a perspective view of a magnetic indexer according to a
second embodiment of the present disclosure; and
FIG. 6 is a perspective view of a third embodiment of the magnetic
indexer affixed to a robot.
DETAILED DESCRIPTION
The following description of the embodiment(s) of the present
disclosure is merely exemplary in nature and is in no way intended
to limit the disclosure, its application, or uses.
With reference to FIGS. 1 and 2, a magnetic indexer 10 in
accordance with an embodiment of the present disclosure is shown.
The magnetic indexer 10 includes a vacuum attachment member 12, a
work piece platform 14, a probe platform 16 and a plurality of
probes 18, 20, and 22. The vacuum attachment member 12 generally
includes members in which a vacuum may be created, so as to affix
the work piece platform 14 to a work piece (described further
herein). It will be understood, however, that any appropriate
system suitable for attaching the work piece platform 14 to a work
piece may be used. Extending generally perpendicular from the work
piece platform 14 are stabilizing members 24 (FIG. 2) which engage
the work piece to ensure that the work piece platform 14 is
substantially parallel to the work piece. A magnet 26 is positioned
on an opposite side of the work piece from the work piece platform
14. The magnet 26 produces a magnetic field which has a central
magnetic axis 26a. Extending from the work piece platform 14 is the
probe platform 16. The probe platform 16 is moveable relative to
the work piece platform 14. A first set of adjustment screws 28
allow for movement of the probe platform 16 in a first axis A. A
second set of adjustment screws 30 allow for adjustment of the
probe platform 16 along a second axis B. Therefore the probe
platform 16 may be moved, relative to the work piece platform 14,
using the first set of adjustment screws 28 and the second set of
adjustment screws 30, in two dimensions.
Affixed to the probe platform 16 are probes 18, 20 and 22. The
probes 18, 20 and 22 are spaced apart so that the probes define a
center axis C. The center axis C is an axis equidistant from, but
parallel to, an axis along which each of the probes 18, 20 and 22
extend.
The probes 18, 20, 22 are affixed to a secondary probe platform 32
which is affixed to the probe platform 16 with a fastener 33. This
allows the secondary probe platform 32 to be removed from the probe
platform 16 without moving the work piece platform 14.
With reference to FIGS. 3 and 4, the effect of each probe 18, 20,
22 is determined by a processor 34. The processor 34 may be any
appropriate processor, however, a microprocessor is able to
determine the effect of the magnetic field on each of the probes
18, 20, 22 and to determine the relative orientation of each of the
probes 18, 20, and 22 to the magnetic field. The processor's 34
determination is displayed on a display device 35. In particular, a
CRT or LCD screen may be used as the display device 35. The
processor 34 can display on the display device 35 a confirmation
that the center axis C is co-linear with the magnetic axis 26a
The magnetic indexer 10 is affixed to a surface or work piece 36
with the vacuum attachment members 12. As discussed above, the
vacuum attachment members 12 may affix the work piece platform 14
to the work piece 36 through any appropriate means. For example, a
vacuum may be created within the vacuum attachment members 12
allowing the work piece platform 14 to be held in place. It will
also be understood that more than two vacuum attachment members 12
may be used depending upon the size of the work piece platform
14.
Below the work piece 36 is a sub-structure or support beam 38. At
the position where a hole must be produced, a magnet 26 has been
placed. The magnet 26 is placed on the beam 38 in a preliminary
manufacturing step before the work piece platform 14 is secured to
the work piece 36. Because of this, the magnet 26 is able to be
easily placed in the exact position where a hole must be produced
for an attachment between the work piece 36 and the beam 38. The
magnetic indexer 10 is placed over a position relatively close to
where the hole must be produced. Then, using the adjustment screws
28, 30, the probe platform 16 is adjusted until the center axis C
is directly over or co-linear with the magnetic axis 26a (through a
process described more fully herein).
Once the center axis C is aligned directly over the magnetic axis
26a, the secondary probe platform 32 is removed so that a drill bit
40 may drill through the probe platform 16 and work piece platform
14 to produce a hole in the work piece 36. It will be understood
that additional drill guide members may be put in place of the
secondary probe platform 32 to increase the precision of the
drilling step performed by the drill bit 40 as it proceeds through
the magnetic indexer 10.
Once the hole is produced through the work piece 36 and the beam
38, the magnet 26 is removed during a clean up process of the
internal area. Furthermore, the magnetic indexer 10 is then removed
from the work piece 36 by pressurizing the vacuum attachment
members 12 to remove the magnetic indexer 10 from the work piece
36. Then, any appropriate fastener is used to affix the work piece
36 permanently to the beam 38.
The exact location of the magnet 26 is determined by locating the
magnetic axis 26a which is a north-south (N-S) pole axis of the
magnet 26. The magnetic axis 26a, also termed the center or field
axis, of the magnet 26 is the center of the magnetic field and the
area where the magnetic field is the strongest. The magnet 26 is
placed on the beam 38 so that the magnetic axis 26a is
substantially perpendicular to the surface of the beam 38.
Therefore, once the work piece 36 is affixed to the beam 38, the
magnetic axis 26a is also perpendicular to the surface of the work
piece 36. Additionally, the work piece 36 should not interfere with
the magnetic field produced by the magnet 26. It will be
understood, however, that as long as the magnetic field of the
magnet 26 is powerful enough for the probes 18, 20, 22 to sense the
field produced by the magnet 26, the work piece 36 may be formed of
virtually any non-magnetic material.
It will be understood that a reference to a single probe 18 in the
following description is exemplary of each of the probes 18, 20, 22
and its description as a single probe is merely for clarity. The
probe 18 is affected by, that is the probe 18 senses, the magnetic
field produced by the magnet 26. One exemplary probe type is a
Hall-Effect probe. In the Hall-Effect probe 18, the magnetic field
produced by the magnet 26 creates a voltage when a current is
running perpendicular to the field in the Hall-Effect probe 18. The
Hall-Effect probe 18 measures the induced voltage produced due to
the magnetic field of the magnet 26. Knowing the induced voltage,
and the current, the strength of the magnetic field is determined
using the equation V.sub.Hned/I=B. According to the equation,
V.sub.H is equal to the Hall-voltage, n is equal to the charge
carrier density, e is equal to the electronic charge, d is equal to
the strip width, and I is equal to the current. This equation
results in B which is the strength of magnetic field. Once the
strength of the magnetic field is known by use of the Hall-Effect
probe 18, the location of the magnetic axis 26a may be determined.
The closer the Hall-Effect probe 18 is to the magnetic axis 26a,
the greater the response in the Hall-Effect probe 18. According to
the first embodiment, the magnetic axis 26a is located co-linear
with the center axis C of the probes 18, 20, and 22 when the
response by each of the probes 18, 20, and 22 is substantially
equal.
The processor 34 determines and processes the affect produced on
each of the probes 18, 20, and 22. The display device 35 displays
the affect determined by the processor 34. The processor 34 may
also indicate which way the probe platform 16 should be moved,
using the adjustment screws 28, 30, to correctly position the
center axis C over the magnetic axis 26a. Then, once each of the
probes 18, 20, 22 indicates an equivalent response, it is known
that the center axis C is positioned directly over the magnetic
axis 26a. At this point, the display indicates that the center axis
C is over the magnetic axis 26a and that the operator should make
no further adjustments. In particular, the center axis C is
co-linear with the magnetic axis 26a of the magnet 26. Once it is
displayed that the center axis C is over the magnetic axis 26a, the
secondary probe platform 32 is removed so that the drill point or
bit 40 may be introduced to produce the desired hole.
With reference to FIG. 5, a second embodiment of a magnetic indexer
system 50 includes a moveable sensor canister 52 with directional
or signaling LEDs 54, 56, 58 and 60 affixed to the top of the
moveable canister 52. Each LED 54, 56, 58, and 60 may include an
array of LEDs such that a strength of the response in a particular
direction can be indicated. Placed centrally and along a center
axis D is a marker 62 which extends through the moveable canister
52 to selectively engage the work piece 36. The center axis D
relates to probes 64, 66 and 68 as center axis C relates to probes
18, 20, 22 according to the first embodiment.
Each of the probes 64, 66 and 68 are connected to a processor 70.
The probes 64, 66 and 68 work substantially similarly to the probes
18, 20 and 22 described in reference to the first embodiment. The
processor 70 also works similar to the processor 34 discussed
above. In the magnetic indexer 50, however, the processor 70
determines the location of the center axis D relative to the
magnetic axis 26a and illuminates the appropriate LED 54, 56, 58
and 60 indicating the direction the moveable canister 52 must be
moved to properly align the center axis D with the magnetic axis
26a. Once the center axis D is placed substantially co-linear with
the magnetic axis 26a of the magnet 26, all four LED arrays 54, 56,
58 and 60 illuminate to show that the center axis D is properly
aligned over the magnetic axis 26a. That is, when all four LEDs 54,
56, 58, 60 are illuminated, they create a visual confirmation that
the magnetic axis 26a is positioned substantially co-linear with
the center axis D. At this point, the marker 62 may be depressed to
form a mark at the position on the work piece 36.
Once the mark has been made, the moveable canister 52 is simply
removed from the work piece 36 and proper chucks may be affixed to
the work piece 36 to ensure that a properly aligned hole is
produced in the work piece 36. Again, once the hole is formed
through the work piece 36 and the beam 38, the magnet 26 and any
debris may be cleaned out of the internal space.
With reference to FIG. 6, a third embodiment of a magnetic indexer
80 is illustrated. The magnetic indexer 80 includes a single probe
82 which is affixed to an arm 84 of a robot 86. It will be
understood that a plurality of probes can also be used with the
robot 86. Only one probe 82, however, is necessary if placed next
to the surface 88 in one location and then moved to another
location along the surface 88 with an exact knowledge of the first
location. Therefore, an effective plurality of probes is simulated
by simply placing and moving the single probe 82 and exactly
recalling the previous placements, and the field measurements, for
each of the previous placements.
A magnet 90, which produces a magnetic field having a central
magnetic axis 90a, is placed near the surface 88 opposite the
magnetic indexer 80. A processor 94 determines the response of the
probe 82 and controls the robot 86. In this way, the robot 86 can
quickly locate the magnetic axis 90a, of the magnet 90, affixed to
the support sheet 92. It will be understood, however, that separate
processors may be used to determine the location of the magnetic
axis 90a and control the robot 86. In addition, once the processor
94 has determined the exact location of the magnetic axis 90a, a
tool may be placed on the robot arm 84 to produce the hole
required. It will also be understood that a plurality of arms may
extend from the robot 86 so that once the position of the magnetic
axis 90a is located, a tool arm simply rotates in place with a tool
extending from the tool arm to produce the hole in the surface 88.
When a robot 86 is used, producing a hole serves to confirm that
the magnet 90 has been properly located.
It will be understood that each embodiment of the present
disclosure does not require a Hall-Effect probe. Any probe which is
sensitive to or which can detect the magnetic field produced by the
magnet 26, 90 may be used in the present disclosure. One
alternative probe is a Three-Axis Magnetic Sensor Hybrid HMC2003
produced by Solid State Electronics Center, a division of
Honeywell. The other portions of the magnetic indexer 10 are
reproduced while simply replacing the Hall-Effect probe 18 with the
alternative probe. If the alternative probe, such as the HMC2003,
is able to determine a magnetic axis in more than one relative
axis, then only one probe may be necessary on the magnetic indexer
10. It is still understood, however, that the single alternative
probe still defines a central probe axis for determining the
magnetic axis 26a, 90a. The alternative probe is still able to
detect the field produced by the magnet 26, 90 and is able to
indicate the magnetic axis 26a, 90a.
It will also be understood that the magnet used in the present
disclosure must have their magnetic axis 26a, 90a properly and
precisely aligned. Therefore, it may be desirable to first test the
magnet 26, 90 using the magnetic indexer 10 to ensure that the
magnetic axis 26a, 90a is properly aligned so that when the magnet
26, 90 is affixed to the beam 38 or the support sheet 92, the
magnetic axis 26a, 90a is substantially perpendicular to the
surface of the work piece 36, 88. This is because only when the
magnetic axis 26a, 90a is produced substantially perpendicular to
the surface is the strength of the field weakened sequentially as
one moves away from the magnetic axis 26a, 90a. It is the magnetic
field acting upon the probes which is sensed by the probes 18, 20,
22; 64, 66, 68; and 82, which are used to determine where the
magnets 26, 90 are positioned. If the magnetic axis 26a, 90a is
angled to the surface (i.e., not perpendicular), the magnetic field
would also not be perpendicular and the precise location of the
magnetic axis 26a, 90a could not be correctly determined.
In addition, the magnetic indexer itself can be calibrated or
zeroed. This means that the central axis of the magnetic indexer
can be precisely determined before performing any tasks with the
indexer. Generally, a magnetic source having a known magnetic axis
can be placed at a zeroed position relative to the magnetic
indexer, so that the magnetic indexer can be zeroed to that
magnetic axis. After this, the precise zeroed position of the
magnetic indexer is known and even greater preciseness can be
attained with the magnetic indexer to locate a magnetic axis.
The various embodiments of the present disclosure thus provide a
means to quickly and precisely detect the locations where holes
need to be drilled in a work piece based on previously made hole
location determinations that are otherwise not visible to an
operator or optical detection machine. The embodiments also allow
for the precise detection of any non-visible landmark as well. That
is, the present disclosure may be used to determine edges of hidden
pieces as well. The present disclosure is especially well suited
for aircraft manufacturing applications, but it will be appreciated
that the embodiments of the present disclosure will find utility in
a wide variety of other manufacturing applications as well.
The description of the embodiments of the present disclosure is
merely exemplary in nature and, thus, variations that do not depart
from the gist of the disclosure are intended to be within the scope
of the present disclosure. Such variations are not to be regarded
as a departure from the spirit and scope of the present
disclosure.
* * * * *
References